I'm running the teams client on Linux (xcfe4 on xubuntu 18.04). It would seem there is some kind of issue with the idle detection in the client. I first noticed it because I couldn't get any notifications on my Android client. When the Android client is set to notify 'Always, even if active on desktop', I get notifications. If its set to 'Only when inactive on desktop' I never get any.
I checked the log, here's an example:
Fri Jan 10 2020 09:28:28 GMT-0700 (Mountain Standard Time) <7288> -- info -- Is foreground set to false
Fri Jan 10 2020 09:28:28 GMT-0700 (Mountain Standard Time) <7288> -- event -- duration: 2.569000005722046, name: desktop_foreground_duration, vdiMode: 0, eventpdclevel: 2,
Fri Jan 10 2020 09:31:05 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:31:06 GMT-0700 (Mountain Standard Time) <7288> -- event -- eventData: s::;m::1;a::4, inactiveTime: 0, name: machineState, vdiMode: 0, eventpdclevel: 2,
Fri Jan 10 2020 09:33:35 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:36:05 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:38:35 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:41:05 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:43:35 GMT-0700 (Mountain Standard Time) <7288> -- info -- Machine has been idle for 0 seconds
Fri Jan 10 2020 09:43:54 GMT-0700 (Mountain Standard Time) <7288> -- info -- emit status indicator state change from Unknown to NewActivity
Fri Jan 10 2020 09:43:54 GMT-0700 (Mountain Standard Time) <7288> -- info -- Added NewActivity (current state: Unknown -> NewActivity)
Fri Jan 10 2020 09:43:54 GMT-0700 (Mountain Standard Time) <7288> -- info -- OS Platform:linux, Release value: 4.15.0-65-generic, Notification type: 17, sourceThreadId: 19:7029d2a8-32a0-4d53-bde5-32a667761daa_acb4d781-2811-47ae-b946-dfd32413a16d@unq.gbl.spaces, messageId: 1578674634231
I stopped using my machine at 09:28 and didn't use it again until well after 09:43 when I received a message. I got no notifications on my Android client when that happened. You can see its saying it was idle for 0 seconds multiple times when in fact, it was idle.
For comparison, I was also running the linux Slack client at the same time. It correctly registers 'idleness' on my machine and appropriately forwards notifications.